<!DOCTYPE html>
<html lang="en">

<head>
  <meta charset="UTF-8">
  <meta http-equiv="X-UA-Compatible" content="IE=edge">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Document</title>
  <link rel="stylesheet" href="./grid.css">
  <style>
    *{
      box-sizing: border-box;
      padding: 0;
      margin: 0;
    }
  </style>
</head>

<body>
  <!--col-
    xs:<576px
    sm:576px ~ 768px
    md:768px ~ 992px
    lg:992px ~ 1200px
    xl:>1200px

    push pull offset
    d-ms-none
    d-ms-block
  -->
  <div class="container">
    <div class="row">
      <div class="col-1">1</div>
      <div class="col-1">2</div>
      <div class="col-1">3</div>
      <div class="col-1">4</div>
      <div class="col-1">5</div>
      <div class="col-1">6</div>
      <div class="col-1">7</div>
      <div class="col-1">8</div>
      <div class="col-1">9</div>
      <div class="col-1">10</div>
      <div class="col-1">11</div>
      <div class="col-1">12</div>
    </div>
  </div>
</body>

</html>